1. Field of the Invention
Embodiments of the invention relate to a stereoscopic image display and a method of adjusting a stereoscopic image of the stereoscopic image display.
2. Discussion of the Related Art
A stereoscopic image display implements a 3D image using a stereoscopic technique or an auto-stereoscopic technique.
The stereoscopic technique, which uses a parallax image between left and right eyes with a high stereoscopic effect. The stereoscopic technique may be divided into a glasses type method and a non-glasses type method. In the glasses type method, the parallax image between the left and right eyes is displayed on a direct-view display or a projector through a change in a polarization direction of the parallax image or in a time-division manner, and thus a stereoscopic image is implemented using polarized glasses or liquid crystal shutter glasses. In the non-glasses type method, the stereoscopic image is implemented by separating an optical axis of the parallax image using an optical plate such as a parallax barrier and a lenticular lens.
The stereoscopic technique makes a viewer perceive that a virtual image is formed in front of or behind the screen on a display panel by a binocular disparity between a left eye image and a right eye image, thereby displaying the stereoscopic image. A stereoscopic feeling of the stereoscopic technique has a complementary relationship with a fatigue of the viewer depending on a degree of the binocular disparity of the stereoscopic image. 3D crosstalk, in which the viewer views a doubled image of the left and right eye images through his/her left or right eye, is generated depending on a method for implementing the stereoscopic image or an optimization degree in the stereoscopic image display using the stereoscopic technique.
When a position of the virtual image is equal to or greater than ±0.3 diopter (abbreviated ‘D’) away from the screen of the stereoscopic image display, the disagreement between convergence and accommodation of the user's eyes increases. As a result, as the virtual image becomes more distant from the screen of the display panel, the fatigue of the viewer increases. The diopter is the reciprocal of a focal length. As the position of the virtual image becomes more distant from the screen of the display panel, the occurrence of the 3D crosstalk may increase.
FIGS. 1A and 1B illustrate examples of a virtual image in the stereoscopic image display.
As shown in FIG. 1A, when light rays of a left eye image L viewed through the viewer's left eye and light rays of a right eye image R viewed through the viewer's right eye cross in the front of the screen, a focal point of a virtual image is formed in the front of the screen. Therefore, the virtual image is formed in the front of the screen. On the contrary, as shown in FIG. 1B, when light rays of the left eye image L viewed through the viewer's left eye and light rays of the right eye image R viewed through the viewer's right eye cross behind the screen, a focal point of a virtual image is formed behind the screen. Therefore, the virtual image is formed behind the screen. Further, as shown in FIG. 1C, when the left eye image L viewed through the viewer's left eye and the right eye image R viewed through the viewer's right eye are displayed on the screen without the binocular disparity, the viewer does not perceive the image displayed on the screen as the virtual image. In FIGS. 1A and 1B, there is the binocular disparity between the same pixel data of the left eye image L and the right eye image R. On the contrary, in FIG. 1C, there is no binocular disparity between the same pixel data of the left eye image L and the right eye image R.
In particular, when the viewer views a virtual image of a region of interest (ROI) of the stereoscopic image in the front of the screen, the fatigue of the viewer increases and the viewer may perceive greatly the 3D crosstalk. The ROI is known as an object of interest (OOI) or saliency and is an object which attracts the greatest interest of the viewer in the stereoscopic image. The viewer mainly views the ROI of the stereoscopic image. The ROI is a region of one screen of the stereoscopic image where is mainly in focus, a close-up people, an object which is greatly contrasted with the surroundings, etc.
As shown in FIG. 2, data of a left eye image and a right eye image separated from the 3D image may be applied to the display panel. The ROI in FIG. 2 is a bust image of a close-up woman in the center of the screen. A resolution of each of the left eye image and the right eye image is adjusted in conformity with a resolution of the display panel, and the left eye image and the right eye image are together displayed on the display panel. As a result, as shown in FIG. 3, the viewer views a virtual image of the ROI in front of the screen because of the binocular disparity of the ROI and views a doubled image of the left eye image and the right eye image, thereby perceiving the 3D crosstalk.